Thermosetting Bonding Sheet Roughness for Gap-Free Semiconductor Assembly
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Solution Overview
Problem
The existing thermosetting sheet bonding method for semiconductor devices often results in gaps between the sheet and the substrate, leading to increased thermal and electric resistance, and insufficient heat dissipation, due to inadequate adhesiveness in the temporarily bonded state.
Innovation Solution
A thermosetting sheet comprising a thermosetting resin, a thermoplastic resin, and conductive particles with specific roughness and packing ratios, which enhances adhesiveness and thermal conductivity by allowing conductive particles to form a thermal conduction path upon curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thermosetting sheet is used for bonding semiconductor devices, then the bonding process can be completed, but gaps occur between the sheet and substrate leading to increased thermal and electric resistance
Solution Approach 1:
The patent changes the surface roughness parameter of the thermosetting sheet to a specific range (Ra: 0.03-0.5 μm, Rz: 0.1-2.0 μm) to optimize temporary bonding performance. This parameter optimization allows the sheet to conform to substrate irregularities and fill gaps effectively during the bonding process, eliminating the gap formation problem while maintaining bonding reliability.
Solution Approach 2:
The patent performs preliminary surface treatment on the thermosetting sheet to achieve the optimal roughness profile before bonding. This preliminary action of controlling surface morphology enables the sheet to adapt to substrate variations during temporary bonding, preventing gap formation before the actual bonding occurs.
2Reliability
If the thermosetting sheet is made smoother for better bonding, then adhesiveness improves, but thermal conductivity decreases due to reduced particle contact
Solution Approach 1:
The patent optimizes two critical parameters simultaneously: surface roughness (Ra: 0.03-0.5 μm, Rz: 0.1-2.0 μm) for adhesiveness and conductive particle packing ratio (≥30 vol%) for thermal conductivity. This dual parameter optimization resolves the contradiction by finding the optimal balance point where sufficient surface conformity for bonding does not compromise particle contact and thermal pathways.
Solution Approach 2:
The patent creates a composite structure combining thermosetting resin matrix with conductive particles (silver, copper, or aluminum) having specific packing ratios. This composite material design allows the resin to provide adhesiveness through controlled roughness while the densely packed conductive particles maintain thermal conductivity pathways, achieving both requirements simultaneously.
3Loss of energy
If conductive particles are increased for better thermal conductivity, then heat dissipation improves, but the sheet becomes more complex and harder to process
Solution Approach 1:
The patent sets the conductive particle packing ratio to a specific threshold (≥30 vol%) and controls particle size distribution (D50: 0.1-10 μm) to achieve adequate thermal conductivity without excessive complexity. This parameter control ensures sufficient heat dissipation while maintaining processability and avoiding over-engineering.
Solution Approach 2:
The patent applies conductive particles with specific properties (material type, size, packing ratio) localized within the thermosetting sheet structure. This local quality approach concentrates thermal conductivity enhancement where needed (in the bonding interface region) without requiring the entire material system to be overly complex, achieving efficient heat dissipation with manageable complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high tight adhesiveness and thermal conductivity, reducing thermal and electric resistance, and improving heat dissipation in semiconductor devices.
Implementation Method 1
the thermoplastic resin temporarily bonds to the substrate at a specific temperature
Implementation Method 2
being subjected to heat curing at a higher temperature to be thereby bonded to the adherend
Implementation Method 3
the conductive particles in the cured thermosetting sheet have a packing ratio P of 30 volume % or more... having a relatively high thermal conductivity after being cured
Data Source
AI summary
Provided in the present invention is a thermosetting sheet including a thermosetting resin, a thermoplastic resin, a volatile component, and conductive particles. The thermosetting sheet has an arithmetic average roughness Ra of 0.1 μm or more and 1.2 μm or less that is measured in a state before being cured.